You see it all over your favorite movies, TV shows and some videogames. A113.

What does it mean?

It means somebody associated with the movie or show studied graphic design and character animation at the California Institute of the Arts.

People like Pixar's John Lassiter, Brad Bird, Andrew Stanton and hundreds others took that class at Cal Arts in classroom number A113. The number has become a running gag for anybody who needs to put a random number on a door, license plate, delivery label or anything else.

Brad Bird apparently was the first to use A113, in an episode of the TV show "Amazing Stories."

A113 has shown up most prominently in Pixar movies. Here's a partial list of the films the secret code has been in: